1. Field of the Invention.
This invention relates to a gimbal system for supporting and orienting an antenna and more particularly to such a system for communicating with a satellite that provides a maximum aperture along with minimum swept volume.
2. Description of the Related Art.
Prior art gimbal systems for antennas used in installations for communications with satellites typically utilize configurations in which the elevation gimbal is mounted on the azimuth gimbal, or have gimbal architecture with non-intersecting X-Y axes. The first of these configurations has the disadvantage of a Keyhole(blind spot) directly overhead( at 90 degrees) and larger swept volume. The second configuration type requires axis counterweighing which also increases size and weight. Many prior art gimbal systems are overweight and over costly for mass production. Prior art systems along the lines indicated above are described in U.S. Pat. No. 5,999,139 issued Dec. 7, 1999 to Benjamin et Al., U.S. Pat. No. 5,517,204 issued May 14, 1996 to Murakoshi et al., and U.S. Pat. No. 4,920,350 issued Apr. 24, 1990 to McGuire et al.
The device of the present invention is an improvement over the prior art in that it provides a simpler, less bulky, lighter weight and less costly antenna gimbal system which does not have an overhead blind spot and is particularly suitable for use in smaller portable installations.
This improved end result is achieved by utilizing a hoop structure, the ends of which are connected to the antenna in a manner permitting pivotal motion of the antenna relative to the hoop structure but not axial motion. The hoop structure and the antenna have a common central axis. The antenna is pivotally supported for rotatable motion on the hoop structure. The hoop structure is motor driven in a manner to drive the antenna so as to rotate the initial Y axis of the antenna to any desired Y axis position between zero and ninety degrees. A second motor is connected by means of a drive gear or pulley to the antenna at one of the ends of the hoop support structure to rotatably drive the antenna on its pivotal support(X axis). With the Y axis of the antenna in its initial xe2x80x9cat rest zeroxe2x80x9d position, the second motor operates to drive the antenna in elevation to any position between zero and eighty degrees. With the Y axis of the antenna in its eighty degree position, the second motor operates to drive the antenna X axis in azimuth to simulate an azimuth positioning axis. The Y axis of the antenna can be positioned as desired at any angle between zero and eighty degrees simultaneously with the positioning of the X axis of the antenna to provide various combinations of azimuth and elevation orientation, providing full hemispherical coverage down to the horizon.
The present invention thus provides a simple structure for obtaining orientations at desired azimuths and elevations with a single drive for obtaining such orientations operating in conjunction with a motor driven hoop structure.
It is therefore an object of this invention to provide an improved gimbal structure with full azimuth and elevation orientation for an antenna which can be used to communicate with a satellite;
It is a further object of this invention to provide a gimbal system for a satellite antenna which is of less swept radius, bulk, weight and cost than that of prior art systems.
It is further object of this invention to provide an improved gimbal system for a satellite antenna using a single drive for both azimuth and elevation with which there is no blind spot at ninety degrees elevation and for which minimum counter weighting is required.
Other objects of the invention will become apparent in view of the following description taken in connection with the accompanying drawings.